Here are the dP vs flow curves for the filters before they are loaded with dirt. The test viscosity is 13.5 cST, equivalent to a 5W30 at around 90 degrees C.
The Royal Purple has a dP of around 465", or 17 psi, at 49 L/min.
Subaru oil pumps will typically flow 55-85 L/min near redline, and they will use a smaller, more restrictive filter than the one tested as well, so they may start bypassing at less than half the rated oil flow, and well before the oil pump starts limiting flow by going into pressure relief (assuming that the RP filter has a typical bypass setting).